I never even thought of using a BEC to power the Pi, that is a great idea. I think I even have one sitting around in my RC parts. Have you ever looked at how clean the power is coming out of it? I noticed a ferrite on the power leads. Did you connect the BEC to the GPIO (Pins 2 and 6) or are you powering it via the MicroUSB?

I've got some adjustable buck converters that I'm using with my 24-volt supply to drop the voltage to run the 12V cooling fans. I may use another one on the Pi, but the power coming out of the inexpensive buck converters isn't the "cleanest", I measured about 120 mV of ripple on 5 V. I suppose before I pass judgement on the converter, I should look at the output of the wall-wart I am using and see how clean it is.

 

@Kyo
Awesome build. I really like the sub frame very ingenious. What steppers did you use?

 

Awesome build. I am looking to build a version of this. Is there a source for a set of plates for this build.

Bruce

 

Thanks for the info.

 

I haven't opened the file yet. But looks good. Does the X axis have a 20x40 rail for a cable tray?

 

Thank you for posting this excellent build.

What are the maximum working dimensions?

 

I am using an inexpensive 19" monitor with my Pi setup, plugged in via a $3 DVI to HDMI cable.

The monitors I have are used Dells, they're older, with CCFL, but they're good panels. Best part? They cost $45 each from Ebay, shipped. Just need to make sure that the monitors have a DVI input. Everything just worked when I plugged it in, no fiddling with settings or anything. These monitors also have an integrated USB hub, so I only need to connect the DVI to HDMI and one USB cable to the Pi, then I can plug the keyboard and mouse into the monitor and position the console a bit further away from the machine.

BTW, I'm running Raspbian and BCNC on my Pi3 to control my C-Beam with a Protoneer shield, it all seems to work well so far, but I am just getting started.

@Kyo: I picked up a 5V/12V BEC and Power Distribution board meant for quadcopters (an ARRIS CC3D Naze32, $12 @ Amazon) the other day and tried it out. Voltages are spot-on, 5.00 and 12.00, they only dip a little bit under load too. Fairly clean power, not perfect, but there was only about 20mV of ripple on the 5V according to my scope after I looped the power out wire through a ferrite and put a load onto it. The Pi seems to run just fine with it, I plugged the power in via GPIO pins 1 and 3. As soon as I can get some sort of case or cover printed out for the board, I will install it on the C-Beam. The 5V output is rated to 3A, plenty for the Pi. The 12V output is limited to half an amp, but that is plenty to spin a few fans, which I all I need the 12V for. The steppers run @ 24V.

 

Kyo, you might take a cue from Mark Carew in the way he designed the XL Gantry Plates for the c-beam. Rather than messing around with trying to get the lead nut bolt spacing exactly right, he just slotted the mounting holes for the lead nuts parallel to the lead screw. This allows you to adjust the position a bit to make up for any issues.

As an aside note, I discovered that this setup also makes the use of anti-backlash nuts irrelevant. Since you have a bit of adjustment on the nut position, you can use the regular non backlash nuts and compensate for backlash by adjusting the position of the two regular nuts. Just put in the leadscrew, and squeeze the nuts together while tightening the mounting screws.

 

I love the design and I think this might be what I go with for my machine.

Two questions:

1. On the BOM it lists http://openbuildspartstore.com/belt-reduction-mount-nema-23-high-torque-series/ but it appears as though OpenBuilds no longer sells them (or they renamed them and I can't find it on their website). Is this a suitable replacement: Threaded Rod Plate - NEMA 23 Stepper Motor

2. I plan on scaling this build to 1000x1000. Looking at the Y axis end plates it has the bearings on the inside of the C-Beam. After reading a lot about screw whip and methods to eliminate it I saw about removing compression on the screw by tightening the lock collar up against the bearing (Video R7v7 Build Videos - SMW3D R7). I'm considering moving the bearing recess to the outside of the plate and using this method. Any thoughts or opinions on that?

EDIT: I guess number 2 would apply to X end plates also.

 

I went back and looked at the model and realized you're absolutely right. I thought about flipping them earlier but for some reason it didn't work out in my head. Awesome job on having the foresight to design them that way. Just have to decide if I want to make any modifications or not. Awesome job on documenting everything. That makes everything 10000 times easier when someone wants to come along and plan a build. The documentation helped me make my decision on this build as opposed to comparable builds which didn't have as good documentation.

 

At what point would the tr8*8 have whip? 1000mm seems to be the max people are pushing them. I'd like to build a bigger machine, but cost is something I'm considering.

 

Kyo, do you have a source for the 10mm leadscrews and nuts? I found a similar type on Ebay in both 10 and 12mm, but lengths not longer than 950mm. Have not found any others. There are lots of Chinese made ball screws out there but nothing compatible with the OpenBuilds nut mounting system.

 

Where do you get taps? I recall a thread on the list somewhere where one of the members was making his own lead nuts, using taps he made from the actual lead screw. I'm not sure I have the facilities to do this accurately.

The TR10x2 is only half the pitch of the OB screws, and would be pretty slow... And Motedis is German and makes no mention of shipping to North AM. Their lead nuts are 13mm thick, 1mm thicker than the OB ones.

 

This is where I found the ones I mentioned:

http://stores.ebay.ca/qtecstore/

 

That's the problem I am having.

Although, I do not want to run anything much over 1000mm anyway. I've been holding off doing a 1000mm machine for just that reason.

However, running the lead screw under tension rather than compression seems like it will solve the problem. I already have the thrust bearings, but the 750mm machine I'm building I've already cut the lead screws and they will be too short for a tension mode to test it out. I can do the Z axis, but that's not really a fair test. Hmm, I have not cut the lead screw for the X axis yet. Mebbe I'll try that.

Thanks a bunch, buddy. Happy building!